This section provides background information related to the present disclosure which is not necessarily prior art.
Residential, commercial and industrial buildings include plumbing systems that provide clean water to the building's inhabitants or occupants and route waste water to a sewer system or other waste water depository. Building and health codes and regulations require such plumbing systems to fluidly isolate the clean water from the waste water to avoid contaminating the clean water and to ensure the clean water is potable. Therefore, waste water conduits and clean water conduits must also be fluidly isolated from each other.
Plumbing systems provide both hot and cold clean water to allow the building's occupants to control the temperature of the clean water. Therefore, plumbing systems often include a boiler or hot-water heater to heat a portion of the clean water entering the plumbing system from a local water source. Heating the water requires considerable energy consumption, which has significant economic and environmental consequences.
A substantial portion of thermal energy in hot water is lost when the water enters a drain as waste water. Accordingly, it is economically and environmentally advantageous to transfer as much of the thermal energy in waste water to the clean water before the clean water is heated in the hot-water heater. A heat recovery system may be employed to extract thermal energy from the waste water and use this thermal energy to preheat the clean water before it enters the boiler or hot-water heater.